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Biomedical subjects

M S Wilson

Publications and source records attributed to M S Wilson.

At least 19 recordsLinked to original sources
PubMed1995

The ability of laparoscopic clips to withstand high intraluminal pressure.

OBJECTIVE: To determine if commercially available clips for laparoscopic surgery become displaced with high intraluminal pressures. DESIGN: In vivo model in which the splenic, renal, and mesenteric vessels together with the gallbladder of anesthetized living pigs were individually occluded using titanium and absorbable clips and then subjected to pressures of 300 mm Hg; and in vitro model in which the procedure was repeated on freshly removed human gallbladders with the attached segment of cystic duct. INTERVENTION: The intraluminal pressure of the occluded segment was increased until (1) the clip was released, (2) the vessel burst, or (3) the predetermined pressure (300 mm Hg) was obtained. RESULTS: A total of 90 clips were examined. No clip could be displaced from any porcine vessel at intraluminal pressures of up to 300 mm Hg. One vessel burst before the predetermined pressure was obtained, the clips remaining intact. Clips placed on the porcine and human models also could not be displaced by a pressure of 300 mg Hg. CONCLUSION: Commercially available titanium and absorbable clips do not disrupt when subjected to high intraluminal pressures. Postoperative bile leaks are more likely to result from necrosis of the cystic duct than displacement of the clip by the pressure within the biliary system.

Animals↗
PubMed1995

Prospective trial comparing Lichtenstein with laparoscopic tension-free mesh repair of inguinal hernia.

A prospective study of 242 patients with inguinal hernia who underwent tension-free mesh repair by the laparoscopic transperitoneal (n = 121) or the open Lichtenstein (n = 121) technique was performed. There was no significant difference in operation time between the laparoscopic (median (range) 35 (20-90) min) and Lichtenstein (40 (20-90) min) procedures. Discharge within 24 h of operation was more common after laparoscopic surgery (89.3 per cent versus 48.7 per cent). Consequently, hospital stay was reduced with this approach (median (range) 1 (1-7) days versus 2 (1-10) days for patients who had a Lichtenstein repair). There was no significant difference in parenteral analgesia requirements or visual analogue pain scores between the two groups. Although use of oral analgesia in hospital was greater in patients who underwent Lichtenstein hernioplasty, this may reflect their longer stay. Rehabilitation to normal activity and return to work was shorter in patients receiving laparoscopic repair (median 7 and 10 days, respectively) than Lichtenstein repair (14 and 21 days) (P < 0.001). Initial results suggest that laparoscopic procedures may be associated with more rapid rehabilitation compared with that of open tension-free mesh surgery. Most patients with inguinal hernia undergoing tension-free mesh repair by either technique would be suitable for day-case surgery.

Adolescent↗
PubMed1995

Recurrent inguinal hernia after laparoscopic repair: possible cause and prevention.

Eleven patients with recurrent inguinal hernia after laparoscopic hernia repair were referred for treatment. A medial recurrence associated with a mature peritoneal sac was identified in each case. The prosthetic mesh medial to the inferior epigastric artery had rolled away from the pubic ramus to expose Hesselbach's triangle. All cases were successfully treated by insertion of a second mesh to cover the defect and overlap the original mesh. To date there have been no further recurrences. Lessons learnt from experience of such laparoscopic transperitoneal hernia repair include that: the prosthetic mesh must be placed so that it reaches or crosses the midline; at least three staples should fix the mesh to the pubic ramus; a large mesh (13 x 9 cm) with a greater surface area should reduce the pressure tending to disrupt the mesh; and bilateral hernia is best managed by inserting a single piece of mesh (28 x 9 cm) fully unfolded as it crosses the midline to ensure coverage of both medial direct defects ('bikini repair'). Application of these principles may reduce the incidence of recurrence after laparoscopic inguinal hernia repair.

Adult↗
PubMed1995

Laparoscopic 'bikini mesh' repair of bilateral inguinal hernia.

Laparoscopic hernia repair using a single piece of mesh was performed in 150 patients with bilateral inguinal hernia. The median operating time was 43 (range 30-90) min with a median hospital stay of 1 (range 1-10) days. In all, 138 patients were discharged within 24 h of operation. The median time for return to normal activity was 7 (range 2-60) days and that for return to work 14 (range 2-60) days. One patient required surgery for a port-site hernia and another for a Veress needle injury to the small bowel. Additional complications included bruising in nine patients, cord seromas in seven and urinary retention in two. There have been no recurrences after a median follow-up of 18 (range 1-38) months. The cost benefits of a short hospital stay and rapid return to work afforded by laparoscopic bilateral hernia repair warrant further evaluation.

Adult↗
PubMed1995

Dietary polyunsaturated fat modifies low-density lipoproteins and reduces atherosclerosis of nonhuman primates with high and low diet responsiveness.

We tested the hypothesis that an increased content of n-6 polyunsaturated fatty acids (principally linoleic acid) in an atherogenic diet of nonhuman primates would decrease atherosclerosis by modifying the composition and decreasing the concentration of plasma low-density lipoprotein (LDL). A species readily susceptible to diet-induced atherosclerosis (cynomolgus monkey) was compared with a less-susceptible species (African green monkey) with dietary cholesterol concentration and saturated or polyunsaturated fat (40% of energy) as variables. In both species, cholesterol concentrations in whole plasma, LDL, and high-density lipoprotein (HDL) were 20-30% lower when polyunsaturated fat was fed, whereas dietary cholesterol increased LDL cholesterol three- to fourfold. LDL was enriched in cholesteryl oleate when saturated fat and cholesterol were fed. Dietary linoleic acid prevented cholesteryl oleate enrichment and promoted cholesteryl linoleate accumulation in LDL. At the same plasma cholesterol concentration, cynomolgus monkeys had higher LDL cholesterol and lower HDL-cholesterol concentrations than did African green monkeys. LDL particle size was significantly (P < 0.001) larger in the group of cynomolgus monkeys fed polyunsaturated fat but tended to be smaller in African green monkeys fed polyunsaturated fat. Dietary polyunsaturated fat protected against coronary artery atherosclerosis in both species. Thus, LDL particle size, per se, was not atherogenic; instead, coronary artery atherosclerosis and cholesteryl oleate enrichment of LDL were more highly correlated. This outcome suggests that information about LDL composition may be more important for understanding the pathogenesis of atherosclerosis than previously suspected.

Animals↗
PubMed1994

An evaluation of five different methods for estimating proliferation in human colorectal adenocarcinomas.

Five different methods of determining cell proliferation have been compared in samples taken from a group of 125 human colorectal tumours labelled in vivo with iododeoxy-uridine (IUdR). The labelling index (LI) was obtained immunocytochemically using monoclonal antibodies against proliferating cell nuclear antigen (PCNA), the Ki67 antigen and IUdR (IUdRimm). Incorporation of IUdR was also determined flow cytometrically (IUdRfcm) and PCNA expression was measured in both formalin- and methanol-fixed tissue (PCNAf and PCNAm respectively). There was significant variation in the results obtained both within and between the different assays. Paired analysis of the data showed that the correlation between the different methods of determining the LI was poor. However, the IUdRfcm LI was significantly correlated with both IUdRimm (r = 0.39; n = 78; P < 0.001 by Spearman's test) and Ki67 LIs (r = 0.32; n = 87; P < 0.001). The IUdRimm LI was also significantly related to the Ki67 LI (r = 0.44; n = 60; P < 0.001). The median IUdRfcm and IUdRimm LIs were significantly higher in the aneuploid vs. the diploid tumours (17.4% vs. 6.2% for IUdRfcm; 23.2% vs. 18.9 for the IUdRimm; P < 0.001 and P = 0.014 respectively by Mann-Whitney U-test) but none of the other proliferative indices showed this relationship. Finally, none of the LIs showed a significant association with the clinical characteristics of the tumours such as stage, grade, age, sex or fixity. The findings of this investigation highlight the need for carefully controlled studies when assessing the value of proliferation markers in solid human tumours.

Adenocarcinoma↗
PubMed1993

The value of exfoliative cytology in the diagnosis of rectal malignancy.

This study has assessed the feasibility and reliability of cytology smears taken from patients with known rectal carcinomas without the use of any special instruments. In a pilot study of 23 patients who all had proved rectal cancer, 19 patients had satisfactory smears, one of which produced a false negative result. The remaining 18 displayed varying degrees of dysplasia (10) or frank malignancy (8). One of the patients with a smear containing severely dysplastic cells had a negative biopsy but had clear clinical and radiological evidence of a rectal tumour. Subsequently, a blind controlled study was undertaken on 29 patients with either carcinoma, proctitis or a normal rectum. All 29 sets of smears were of diagnostic quality and were correctly diagnosed as benign or malignant by the cytologist who had no knowledge of the clinical diagnosis. This is a rapid and simple diagnostic test which, if positive for malignancy, allows treatment to be planned at the first consultation. In combination with a forceps biopsy, the rate of positive diagnosis may be increased. A dysplastic smear adds to the level of clinical suspicion and confirms the need for biopsy of a lesion.

Adenocarcinoma↗
PubMed1993

An assessment of the reliability and reproducibility of measurement of potential doubling times (Tpot) in human colorectal cancers.

An assessment has been made of the reproducibility of measuring tumour proliferation using in vivo iododeoxyuridine (IUdR) labelling and flow cytometry. The variation that occurs between different institutions (Paterson Institute for Cancer Research, Manchester and the Gray Laboratory, Northwood), different observers and different runs on the same flow cytometer have been measured on 139 samples from 53 patients with colorectal cancer. The results demonstrate that the IUdR technique for measuring tumour proliferation is reproducible. Correlations were seen between measurements of Tpot obtained by different individuals and on separate machines. However, direct comparisons of the measured parameters showed that there were highly significant differences in the values obtained between institutes and observers (P < 0.001). Despite these variations, there were still significant detectable differences in Tpot measurements between individual tumours (P < 0.001). Analysis of the results obtained by running the same samples on two separate occasions on the same machine showed that the technique was highly reproducible and that the staining procedure was stable. Eighty per cent of the samples were similarly assigned to either above or below the median Tpot value, regardless which observer/laboratory combination was utilised. These data suggest that large clinical trials using Tpot should employ a single centre and a single individual to prepare, run and analyse samples.

Adenocarcinoma↗
PubMed1993

Intra-tumoral heterogeneity of tumour potential doubling times (Tpot) in colorectal cancer.

Intra-tumoural heterogeneity of proliferation has been assessed by taking multiple biopsies from 30 colorectal cancers. Following in vivo IUDR labelling, dual parameter flow cytometry was used to measure tumour DNA index (DI) and labelling index (LI) and to derive DNA synthesis time (Ts) and potential doubling time (Tpot). Heterogeneity was seen for all parameters under investigation. Overall coefficients of variation (CV) and logarithmic transformation of Ts and Tpot (due to their non-gaussian distributions) indicate that LI (CV 25%) was the most variable parameter. Intra-tumoral heterogeneity in Tpot (lnTpot CV = 22%) was less than inter-individual variation (CV = 63%), suggesting that this variation should not be a limitation to the possible usefulness of this technique as an independent prognostic indicator. Correlations of Tpot values were examined between the shortest, the median and the value for a pooled homogenate sample from a single tumour. Using an homogenate, it was possible to accurately predict classification of tumour Tpot values as being below the median ('fast tumours') in 15 of 19 cases (79%). The data suggest that assaying an homogenate may allow a more rapid analysis of a multiply sampled tumour.

Adenocarcinoma↗
PubMed1993

Non-surgical intrauterine artificial insemination in bitches using frozen semen.

A total of 46 bitches were inseminated directly into the uterus using non-surgical insemination procedures; the technique used in six bitches involved specially designed metal catheters and abdominal fixation of the cervix, whereas the remainder were inseminated by passing a flexible plastic catheter through the cervix using direct endoscopic visualization to facilitate the process. Twenty-seven bitches were inseminated with semen frozen at the clinic; the remainder were inseminated with imported semen. Insemination timing was based on endoscopic assessment of the vaginal mucosa, vaginal cytology and blood progesterone concentration determined using a rapid, qualitative enzyme-linked immunosorbent assay (ELISA) kit. Each bitch received between 50 x 10(6) and 200 x 10(6) total spermatozoa per insemination; post-thaw motility varied from 10 to 80%. Two inseminations were performed 48 h apart in the majority of bitches. An overall pregnancy rate of 80% (37/46) was obtained with a mean litter size of 5 +/- 3.14. Subsequent pregnancy rates were comparable for both techniques and both were considered to be effective methods of inseminating frozen semen. Considerably fewer spermatozoa were inseminated in many of these bitches than have previously been reported. In a series of seven bitches using the semen from one dog, each bitch received two inseminations of 30-35 x 10(6) live normal spermatozoa per insemination. A pregnancy rate of 85% (6/7) and a mean litter size of 7.8 was achieved. Rapid ELISA progesterone kits were used to identify the optimum time for insemination.

Animals↗
PubMed1992

Common bile duct diameter and complications of endoscopic sphincterotomy.

To assess the relationship between distal common bile duct (CBD) diameter and the incidence of an immediate complication following endoscopic sphincterotomy (ES), all patients undergoing ES between January 1986 and October 1990 were studied. The overall risk of an immediate complication following ES in 655 patients was 5.6 per cent (37 patients). Patients with calculi were at greater risk if the distal CBD was dilated (P < 0.001); the complication in those with stones was most likely to be haemorrhage (81 per cent). The relative risk of a complication increased ten times if the distal bile duct diameter was > 0.8 cm. Patients with stricture of the distal CBD did not have a significantly greater risk of complication than those with stones (9.7 versus 4.9 per cent). There was no significant difference between the mean distal CBD diameter of those with stricture and controls (0.61 versus 0.44 cm).

Adult↗
PubMed1990

Malignant histiocytosis. A reassessment of cases previously reported in 1975 based on paraffin section immunophenotyping studies.

Malignant histiocytosis (MH) is a term that has been used to describe a syndrome in which there is a systemic proliferation of cells that have the cytologic appearance of atypical histiocytes. Biopsy materials from 15 patients with malignant lymphoma diagnosed as malignant histiocytosis in a previous study reported in 1975 were analyzed by a panel of antibodies and reclassified using current nosologic concepts of malignant lymphoma. The antibodies used comprised reagents detecting a formalin-resistant epitope on B-cells (L26), T-cells (anti-CD3, anti-leu 22 [CD43], and UCHL1 [CD45RO]), monocyte/macrophage-derived cells (KP1 [CD68]), as well as antibodies that detect leukocyte common antigen (PD7 [CD45RB]), and a formalin-resistant epitope of Ki-1 (Ber-H2 [CD30]). The authors found that nine lymphomas had a profile consistent with T-lineage, including six in which Ki-1 (CD30) was coexpressed, and two were B-lineage. Three lymphomas showed no specific lineage characteristics although two were Ki-1 (CD30) positive, and none had expression of KP1 (CD68). The 12 lymph node biopsy specimens showed a variety of patterns of involvement, including sinusoidal, paracortical, and diffuse; the spleens showed predominantly red pulp involvement. A 15th case was believed most consistent with a virus-associated hemophagocytic syndrome. These findings support previous suggestions that the majority of cases diagnosed as MH represent T-lineage-associated hematolymphoid neoplasms, and that only a rare case will be of monocyte/macrophage origin. It is suggested that the term MH be subsumed under the rubric of large cell lymphoma and unless there are compelling immunohistochemical data to support a histiocytic origin, that the term MH be abandoned in favor of a more accurate descriptive term, such as sinusoidal large cell lymphoma.

Adolescent↗